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Título: Nutrient dynamics of the highly productive C4 macrophyte Echinochloa polystachya on the Amazon floodplain
Autor(es): Maria Teresa Fernandez Piedade
W J Junk
S P Long
Assunto: Areas alagaveis
Echinochloa polystachya
Capim aquatico C4
ISSN: 0269-8463
Revista: Functional Ecology
Volume: 11
Resumo: 1. Echinochloa polystachya forms extensive monotypic stands on the lower levels of the Amazon floodplains, During its annual growth cycle c. 100t (dry mass) hdl of biomass is formed as the floodplain is being submerged (December-September) and a phase of death and decomposition occurs when the water has retreated (October-November). This study examines the mineral nutrient dynamics of this plant and its potential significance to the nutrient status of the floodplain,2. Echinochloa polystachya was sampled monthly from a study site in the central Amazon. N, P and K contents for different plant organs were determined and net uptake calculated from concurrent measurements of dry matter production and turnover,3. Leaf N, P and K contents were c. 20, 1.7 and 19 g kg(-1), values typical of nutrient-replete stands of C-4 plants. Stem concentrations were c. 12% of those of the leaves. Net N and P uptake followed the rise in the river level, whilst K appeared independent of water level.4. The vegetation accumulated 377, 51 and 1136 kg ha(-2) of N, P and K, respectively, during the growth phase. Over a possible 5000 km(2) of these stands in the Varzea, this represents a massive sequestration of nutrients in the flood phase and a high release during the following low-water period. It is suggested that the E. polystachya stands could have a role in maintaining the nutrient status of the Amazon floodplain.
ISSN: 0269-8463
Aparece nas coleções:Coordenação de Dinâmica Ambiental (CDAM)

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